Venezuela is the living proof. They can't rely on their fiat anymore because of the hyperinflation and I just feel so much pity when I read the most of their people turn to games to mine some currency there. The US dollar is very close to experience such fate so let us thank Trump for great participation.
So this is really possible to happen this days? well, I will not believe it as long as usd is still there. Lets see if cryptos can replace usd in the future but I bet it will really never happen.